Zeolite, silica gel, etc. have conventionally been widely known as a moisture absorbent (a dehumidifying agent), and desiccant moisture absorption (dehumidification) apparatuses utilizing these are commercially available (see Japanese Patent Laying-Open No. 2000-126540 (patent document 1), Japanese Patent Laying-Open No. 2010-69428 (patent document 2), etc. for example). Such a dehumidifier utilizing zeolite, silica gel, etc. exposes an air permeable honeycomb rotor having zeolite, silica, etc. applied thereto to indoor air to adsorb moisture in the air, and, to extract the moisture therefrom, employs a heater to blow high temperature air to heat it to be water vapor and thus released. High temperature air containing the water vapor is cooled by a heat exchanger to extract moisture to thus dehumidify indoor air.
Conventional moisture absorbents such as zeolite and silica gel require large heat energy in order to desorb moisture. More specifically, these moisture absorbents after having adsorbed moisture need to be heated to such a significantly high temperature as 200 degrees centigrade or higher to have the moisture removed therefrom so that they are recycled to have a moisture absorbable state. The above desiccant moisture absorption (dehumidification) apparatus adopts a structure which divides a moisture absorbing portion and a heated portion and causes a rotor to rotate to allow constant moisture absorption and desorption, and accordingly, requires constantly energizing a heater, which consumes large electric power and also has a possibility of firing by heating at high temperature. Furthermore, the blown air is also heated after dehumidification and thus discharged, which results in excessively high room temperature, and there is also a concern voiced about using the apparatus in the rainy season having high temperature and high humidity in particular. Furthermore, for the conventional desiccant moisture absorption apparatus to desorb moisture and change it into water, it is also necessary to cool air once heated.
In contrast, Japanese Patent Laying-Open No. 2002-126442 (patent document 3) describes a gel sheet which uses a gel having a water absorption property varying across a phase transition temperature to remove moisture and absorb water.